What contraception options are effective in preventing pregnancy in 99 out of 100 women, such as Mirena (levonorgestrel), Nexplanon (etonogestrel), or Depo-Provera (medroxyprogesterone acetate)?

Contraceptive Options That Prevent 99/100 Women from Getting Pregnant

Both Mirena (B) and Nexplanon (C) prevent pregnancy in more than 99 out of 100 women, with typical use failure rates of 0.2% and 0.05% respectively, making them the most effective reversible contraceptive options available. 1

Efficacy Data from CDC Guidelines

Most Effective Methods (>99% efficacy)

• Nexplanon (etonogestrel implant): 0.05% typical use failure rate, meaning 99.95 out of 100 women will not get pregnant 1
• Mirena (levonorgestrel IUD): 0.2% typical use failure rate, meaning 99.8 out of 100 women will not get pregnant 1

Less Effective Options from Your List

• NuvaRing (contraceptive ring): 9% typical use failure rate, meaning only 91 out of 100 women avoid pregnancy 1
• Depo-Provera (DMPA injection): 6% typical use failure rate, meaning only 94 out of 100 women avoid pregnancy 1

Key Clinical Distinctions

Long-acting reversible contraceptives (LARCs) like Mirena and Nexplanon are superior because they eliminate user adherence issues. Unlike methods requiring regular administration, these devices work continuously once inserted, which explains their dramatically higher real-world effectiveness 1.

Why NuvaRing Falls Short

• Requires monthly insertion and removal by the user 1
• User error significantly impacts effectiveness, dropping it to 9% typical use failure rate 1
• Perfect use efficacy is 0.3%, but typical use reflects real-world adherence challenges 1

Why Depo-Provera Falls Short

• Requires injections every 3 months 1
• Failure rate of 6% with typical use reflects missed appointments and delayed injections 1
• Perfect use efficacy is 0.2%, but adherence to the quarterly schedule is challenging for many patients 1

Clinical Recommendations

The American Academy of Pediatrics and CDC recommend counseling patients about the most effective methods first, starting with LARCs (implants and IUDs). 1 This approach prioritizes methods with the highest real-world effectiveness.

Nexplanon Advantages

• Single-rod subdermal implant effective for 3 years (FDA-approved) or up to 5 years (extended use supported by evidence) 1, 2
• Highest continuation rate at 84% at one year 1
• Ideal for patients who cannot use estrogen-containing methods 1, 3

Mirena Advantages

• Levonorgestrel-releasing IUD effective for 5 years (FDA-approved) or up to 7 years (extended use supported by evidence) 1, 2
• 80% continuation rate at one year 1
• Provides additional benefits including reduced menstrual bleeding 1

Common Pitfall to Avoid

Do not confuse "perfect use" with "typical use" efficacy when counseling patients. Perfect use assumes flawless adherence, which rarely occurs in clinical practice 1. Typical use data reflects real-world effectiveness and should guide contraceptive counseling 1.

Answer: B (Mirena) and C (Nexplanon) both achieve >99% pregnancy prevention. If forced to choose only one answer, Nexplanon (C) has the slightly higher efficacy at 99.95% versus Mirena's 99.8%. 1